1. Field of the Invention
This invention relates to a gyro, especially to a gyro which relies upon vibration to detect a rotational signal. Further, this invention relates to a gyro which has two rotational axes to be detected.
2. Description of Related Art
A conventional gyro is shown in U.S. Pat. No. 2,716,893. In that type of gyro, a rotation is detected by sensing a Corioli's force. Therefore, a force of inertia must be applied to a member which receives a Corioli's force. Further the member has to face two rotational axes in order to detect two rotational signals. The member which receives a Corioli's force should face toward two rotational axes and a constant force of inertia should be applied thereto. A conventional gyro includes an electric motor to rotate the member which receives a Corioli's force and detects a Corioli's force when the axis of the member matches with the rotational axis. Such a conventional gyro has drawbacks as follows. (1) An inertia force is generated by a rotational movement of a member by an electric motor. The member has mechanical frictional parts such as bearings. Therefore, a wearing of mechanical parts shortens the gyro life. Further, the electric coil of the motor loses power as time passes. (2) Because the member is rotating, the axis of the member only briefly matches the detection axes to detect a Corioli's force. Therefore, a successive detection of a Corioli's force of the member is not possible. (3) Accuracy of detection is relatively low. (4) Because a rotational movement is involved, the mechanism must be complicated in order to support the rotation. The size of parts is important and assembly of the parts is difficult. Each gyro must be adjusted when it is assembled.